Fuel injection device



Oct. 23, 1951 w. B. SMITS FUEL INJECTION DEVICE Filed July 1, 1948 FIGBINVENTOR WYTZE BEYE SHITS BY v I v Q AGENTS Patented Oct. 23, 1951 FUELINJECTION DEVICE Wytze Beye Smits, Voorburg, Netherlands, assignor toSmitsvonk N. V., The Hague, Netherlands Application July 1, 1948, SerialNo. 36,398 In the Netherlands July 23, 1947 2 Claims.

The invention relates to a fuel injection device having a body in whicha fuel duct is formed and which is adapted to be mounted in the wall ofa cylinder of an internal combustion engine.

The invention has for its object to provide, for engines operating withfuel injection and electrical ignition, one single device which is botha fuel injector and a spark plug. It consists in this that electrodesare mounted on the body of the injector near the exhaust opening of thefuel duct thereof, said electrodes being separated by insulating orsemi-conductive material and provided with means for their electricalconnection and said electrodes constituting together with saidseparating material a low tension spark plug adapted to be actuated bydischarge currents of a condenser. The combination of such a fuelinjection device and a spark plug of the sliding or creeping spark typeappears to lead to very simple constructions.

A simple construction of the fuel injecting spark plug is obtained, whenthe fuel injection device is provided with the conventional needlevalve, which is periodically opened by the pressure of the fuel itself,and annular electrodes are arranged coaxially with respect to saidneedle valve. The needle valve is adapted to be axially moved in thebody of the device, and at the end of said body, at which end the fuelduct opens, the

parts of the spark plug are held together by a :2

screw ring screwed on said end of the body. At least one of theelectrodes is connected to a conductor which is insulatedly passedthrough said body.

Instead of an injection device provided with a needle valve other knowninjection systems may be used. The electrodes may extend along the wallof a conical recess at the active end of said body. They may also besituated in a plane which is at right angles to the main axis of thebody of the fuel injecting spark plug.

For the elucidation of the invention reference is made to theaccompanying drawing in which, by way of example, three differentembodiments of the invention are illustrated in part.

Figure 1 is a fragmentary sectional view, with a portion thereof inelevation, of the preferred form of the invention;

Figure 2 is a fragmentary view partly in section and partly in elevationof a modified form of the invention; and

Figure 3 is a fragmentary view partly in section and partly in elevationshowing another modification of the invention.

In Figs. 1-3 of the drawing l designates the metal body of a fuelinjecting spark plug. This body is so constructed that it can be screwedin the wall of the cylinder of an internal combustion engine. Mountedwithin the body I is an axially movable needle valve 2, which is pressedby a spring (not shown) with its conical point 3 against a seat 4.Thereby the fuel injection duct 5 is normally closed. The needle, whichengages the bore 6 of the body I as a piston, closes a chamber 1. Fuelis periodically supplied through the passage 8 under higher pressurethan obtains in the combustion space of the engine. The fuelperiodically lifts the needle 2, so that the duct 5 is opened and fuelis injected into the cylinder of the engine.

In Fig. l a ring 9 of insulating or semi-conductive material is providedin a recess at the active end of the body I. Enclosed by this ring anannular electrode 10 of refractory electrically conductive material ismounted on the surface of that body I and contacts the lattermetallically. A second annular electrode H of electrically conductivematerial is partly embedded in ring 9 and is separated from theelectrode [0 by said ring. The annular electrode H is connected to aconductor 12, which is insulatedly passed through the body I byinsulating material 13. On electrode H a ring of insulating material l4and on the latter other rings [5 and I6 are placed. Ring [5 serves tocompensate the different dilations of the various parts of the device.The spark plug built up of rings is kept assembled by a screw ring llscrewed on the end of the body I.

As soon as a spout of fuel is injected into the cylinder space a sparkgenerated by the discharge current of a condenser is produced betweenthe electrodes l0 and II. This spark creeps across the surface of theseparating member 9.

The embodiment as shown in Fig. 2 is pro vided with a ring 18 ofinsulating or semi-conductive material in which the annular electrodesI9, 23 are embedded. Ring l8 snugly engages the end surface of the mainbody I. Just as in Fig. l the inner electrode H3 is connected to aconductor insulatedly passed through body I and the outer electrode 20metalically contacts screw rin I! which is screwed on the end of saidbody.

In the embodiments according to Figs. 1 and 2 the electrodes of thespark plug are situated in or form part of the wall of a conical recessat the bottom of which the injection duct 5 terminates. In Fig. 3 theactive surface of the fuel injecting spark plug is plane and at rightangles to the main axis of the body I. Both annular electrodes 2|, 22are embedded in the separating ring 23 of insulating or semi-conductivematerial. Said ring is mounted concentrically to the injection duct 5and is kept in its place by the screw ring IT. The outer electrode 22 isconnected to a conductor (not shown) which is insulated'ly mounted inthe body I. By means of this fuel injecting spark plu the dead space inthe cylinder of the engine can be restricted to a minimum.

Within the scope of the invention many other constructions are possible.A plurality of concentric electrodes may be provided. These electrodesneed not have an annular shape. Other injection systems than the oneshown may be used. The main feature of the invention is the combinationof a fuel injection device and a spark plug in a single unit.

What I claim is:

1, A combined fuel injection device and spark plug for internalcombustion engines comprising an outer body adapted to be mounted in thewall of an engine cylinder, a fuel supply duct passing through said bodyhaving an outlet opening, a valve provided in said supply duct having aseat positioned inwardly of said outlet opening, said body, duct andvalve constitutin the injection device, at 'least two ring-shapedelectrodes positioned coaXiall-y around the outlet opening of saidsupply duct and below said valve, an insulating member having at least aportion thereof positioned below said valve interposed between andmechanically connecting said electrodes, the exposed end face of saidinsulating member serving to support the sparks sweeping between saidelectrodes across said end face, means insulatedly passing through saidbody for the electrical connection of at least one of said electrodes,the other electrode contacting a grounded part of the device, saidelectrodes and said separating member constituting a condenser operatedsurface discharge spark plug in the form of an individual unit, and aclamping ring for securing said unit detachably to the outer body.

2. A combined fuel injection device and spark plug according to claim 1,in the active end of which a recess is formed, the fuel supply ductopening in the bottom of said recess and the individual unit, consistingof the electrodes and the insulating member, constituting at least partof the wall of said recess.

Wi'r'rzE BEi'rE SMITS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,205,422 Arnold Nov. 21, 19162,255,203 Wiegand Sept. 9, 1 941

